Method of making measuring instrument pointers



May 9, 1939. H. L. BERNARDE I 2,157,845

V METHOD OF MAKING MEASURING INSTRUMENT POINTERS Filed Oct. 9, 1956wnmassss: INVENTOR Henry Lfierflarde. v

QZWW i Patented 9, i939 r 2,157,845 urn-non or MAKING mascara ms'mumnmrom'mns mm, 1.. Bernarde, Kearny, N. J., minor to Westinghouse Electric& Manufacturing Company, East'Pittsburgh, Pa., a corporation ofPennsylvania I Application October 9, 1986, Serial No. 104,828 2 Claims.29-148) The invention relates to electrical measuring instruments, andparticularly, to an improved construction for the indicating pointer 01small instruments, such as ammeters, volt meters and inlig. 1.

By way of example, the pointer illustrated comprises a body portion 2,terminating at one end in an indicator or target 4, and atthe'other endin a cross-piece having an aperture '6 for securing the ment movement.

5 the like. entire structure to a pivotally mounted portion of gDlillculty has usually been experienced in the instrument movement, Thecross arms 8 are manufacturing the indicating pointers for small for thepurpose of receiving weights of any desired measuring instrumentsbecause of the dimculty .type to properly balance the entire structureabout in making the'polnter sufficiently light for acthe aperture 8. Ifdesired, and as indicated in 10 curacy, and at the same time, heavyenough for Fig. 2, the pointer maybe bent at anintermediate 1o practicaloperation. In view of the small values portion It, so that the target 4may readily pass of energy involved, a pointer oi the required over adial plate which is usually at a plane higher mechanical strength isusually too heavy, giving than the portion of the instrument movement aninaccurate reading on small energy values and, engaging the aperture 6.

because of its inertia, causing over-shooting when It is understood, ofcourse, that the form of the 15 the available energy is suilicient.pointer may be varied within wide limits, the il- When the pointer ismade sufliciently light for lustration being merely of one type to themanuaccurate operation, particularly inthe case of i'acture of which theinvention is applicable. alternating-current instruments, pointer vibra-It is customary in the manufacture of instrution occurs at some criticalfrequency, which of ment pointers n a large scale, to cut or blank 20course, isundesirable. the pointers from a sheet of desired material,

The ideal pointer would be one in which the and it is preferred thatthis expedient be used in thickness tapered decreasingly from the base,the present invention although quite obviously where it is connected tothe instrument moveother expedients may be used. I

ment, toward the pointer end or target which 00- In the preferred mannerof practicing the in- 25 operates with the usual scale. This would givethe vention, a sheet of light-weight material, such as desired strengthat the. base where it is needed, aluminum, having a width substantiallythe same and the overall weight would not be sumcient to or slightly inexcess of the length of the pointer 'cause inertia troubles orinaccuracy.- desired, is diped edgewise into a bath of cor- In practice,however, it has been diflicult, it rosive material, oramaterial whichreacts chemi- 30 not impossible, from a practical point of view, tocally with the metal of the pointer, spch as caustic make a taperedpointer in quantity production at soda in the case of aluminum, andsubmerged in a reasonable cost. It is possible, of course, to roll thebath the desired extent, substantially the each pointer separately tothe desired taper, or to length of th Pointer fr the p of target 4 t0roll a sheet longitudinally to taper in thickness the cross-piece. Thesheet is then raised at such from one edgetotheother and blank thepointers a rate of speed to obtain a desired reduction in laterally ofthe sheet. Both of these expedients the thicknessof the sheet at theedge dipped into introduce manufacturing difliculties and excesthe bath.Obviously, as the sheet isdipped and sive cost and even greaterdifiiculties are en-, raised, the edge inserted into the bath will be 40countered in producing a tubular pointer having subjected longest to theaction of the corrosive the desired taper. material, and such subjectionwill vary in time.

It is an object of the present invention, therefrom the maximum at suchedge to a minimum at i'ore, to provide a method of forming or manu-- theportion 01' the sheet adjacent the surface or iacturing an indicatinginstrument pointer which the bath when the sheet is emer is cheap andefiective, and at the same time, re- Of course, the desired result maybe obtained 45 suits in a pointer of desired mechanical characby asingle dipping and withdrawal, or by sucteristics. cessive clippingsuntil the desiredithickness or Other objects or the invention will beapparent taper is obtained from the following description when read incon- The sheet may then be cleaned in any desired nection with theaccompanying drawing,. in maner and the pointers blanked from. it withthe 50 which: target end adjacent the thinnest edge of the sheet. Figurel is a plan view of a pointer ccnstruct- The pointers may then be bentas indicated in ed in accordance with the invention; and Fig. 2, andsuitably painted or otherwise treated Fig.2 is a side elevation of thepointer shown to make them ready for mounting on the instru- In the caseoi tubular pointers, aluminum tubing, or other desired metal tubing, iscut in lengths corresponding to the length of the pointer, and thepieces dipped axially into the bath and withdrawn. As in the case of thesheet material, the tube walls will be tapered in thickness a desiredamount depending upon the duration of the dipping operation or thenumber of dips to which the tube is subjected,

Although aluminum is a preferred material for pointers of this generalcharacter because of its light weight, quite obviously other materialsare available and may be substituted therefor. The method described isapplicable, however, except that a different corrosive or etching bathmay be required, depending upon the-material of the pointer.

I claim as my invention:

1. The method 0! manul'acuring a-pointer having a tapered thickness fromthe point to the base thereof, which comprises dipping a piece of sheetmaterial into a corrosive bath to a depth corresponding to the desiredlength of the tapered portion and withdrawing it at such speed that aprogressively increasing amount of material is removed from the sheet toform the desired tapered thicknes, and cutting a-pointer of desiredshape from said sheet material.

2. The method of forming a pointer of tapered thickness from the pointto the base thereof which comprises dipping a metal sheet of constantthickness edgewise into a bath of etching fluid and withdrawing itgradually to progressively remove the metal from the sheet to taper itsthickness from one edge to the other, and cutting from said sheetpointers of an increasing tapered thickness from the point to the basethereof.

, HENRY L. B ERNARDE.

